The present invention relates to an assembly including a flexible hub for clamping the flexible hub to a shaft or the like and, more particularly, relates to a flexible hub assembly including a flexible hub and a tapered engagement surface for selective clamping and unclamping of the flexible hub to a shaft or the like.
One approach for transferring the rotation of a shaft or the like to a power takeoff element (e.g. a pulley, gear or sprocket) to thereby drive the element includes securing the power takeoff element to the shaft with sufficient clamping force such that torque, thrusts or combinations of these loads are reliably transmitted from the shaft to the power takeoff element and, ultimately, to the driven element associated with the power takeoff element. Accordingly, hubs have been developed for interconnecting power takeoff members such as bevel gears, pulleys and sprockets to rotating shafts and the like. To insure that the shaft loads are adequately transmitted to these rotation transferring elements and to prevent intolerable wear on the shaft, the hubs must clamp the shaft with sufficient purchase to insure that no slippage occurs therebetween. Representative structures of typical clamping hubs of this type are disclosed in U.S. Pat. Nos. 2,467,819, 3,127,202, 3,042,433 and 4,202,644.
However, these known locking hubs suffer from several recognized disadvantages. For example, in one known type of locking hub, a split ring member with a conical inner surface is superposed over another cylindrical hollow member having a conical outer surface. The conical surfaces of the two cylindrical hollow members slope in opposite directions. The shaft is disposed inside the inner cylindrical hollow member while the power takeoff element is disposed around the outer surface of the outer cylindrical hollow member. Adjustment or loading bolts are selectively rotated to cause axial forces to be directed against the two cylindrical hollow members to cause relative movement between the hollow members. As the cylindrical hollow members move relative to one another, the inner cylindrical hollow member progressively clamps the shaft while the outer cylindrical hollow member progressively expands against the power takeoff element. However, to achieve a non-slipping clamping action on the shaft and a non-slipping engagement with the power takeoff element, a relatively significant torque must be applied to the adjustment or loading bolts to continue to cause relative movement between the two cylindrical hollow members as the wedging action between the two members is increasingly resisted by the shaft on the inside diameter and the power takeoff element on the outside diameter. In fact, the torque required can typically be so great that the design of such locking hubs is limited by the yield strength of the torque applying tool, such as, for example, an Allen wrench. Due to this design constraint, the heat treatment, and thus the strength, of these steel hubs must be limited so that the yield strength of the adjustment tool is not exceeded. Accordingly, the strength of the steel, and its corresponding locking power, are limited. An additional disadvantage of these relatively moving wedge-shaped element type locking hubs is that the inner diameters of many conventional power takeoff elements such as sprockets, gears, pulleys and the like, is limited. Accordingly, if the locking hub is to be positioned between the shaft and the inside diameter of the power takeoff element--that is, flush mounted within the power takeoff element--the locking hub must necessarily have a limited radial extent and this tends to limit the locking power of the hub since the relatively small size of the hub limits the amount of strength material, such as metal, from which the hub can be formed. Yet another disadvantage of the known locking hubs is that effective operation of these hubs requires the user to accurately and reliably turn each adjustment bolt, in a predetermined sequence, to a predetermined torque value and this heavy reliance on the user's care and knowledgeability limits the dependability of these known hubs.